Carbon Brushes and Shims

Abstract:

Carbon brushes transfer electric current from the motor housing to the commutator on the motor shaft. The motor housing is stationary. The commutator spins rapidly when the motor is on.
Carbon brushes are continuously worn down where they contact the commutator. Worn carbon brushes can be too short to reach the commutator. Carbon brushes that do not reach the commutator prevent motors from starting. Worn carbon brushes must be replaced.